Industries such as food and beverage, oil and gas, pulp and paper, and waste water treatment utilize filtration technology. The filtration removes solids from the medium in which the particulates are carried. The filtration process may be accomplished with a single process and filter, or multiple different types of filtration using different filtration equipment can be used with the medium in order to achieve a desired removal of particulates. One such filtration system utilizes a spinning filter, sometimes called a hydroclone, that receives feedwater with particulates therein. A spinning flow pattern is developed within the hydroclone so that heavier solids within the feedwater are moved by centrifugal force to the inside wall of the hydroclone for removal, or down into a circulation loop for removal at another time.
In a self-cleaning hydroclone filter system, medium and lighter particulates engage a self-propelled cleaning unit that spins around a filter media or screen that filters out these particulates from the feedwater. Filtered water is then removed from the hydroclone and is moved downstream to a storage tank, subsequent filtration station, or anywhere else desired. The spinning filter unit can have one or more brushes that continuously wipe off the filter media as they spin around the filter media to clean it and help prevent it from being dogged or fouled. The particulates removed by this cross-flow portion of the hydroclone are likewise moved down into the circulation loop via the flow path established within the hydroclone, or disposed of from the system.
Although capable of filtering particulates from feedwater, such filters ultimately become clogged in that particles impinge themselves within the filter media thus reducing the system's filtering capacity. The flow within the filter may push particulates against the filter media causing them to become stuck within gaps of the filter media, and unable to be swept off by the spinning brush. Over time, the system must be shut off and the filter media removed and serviced in which the fouled filter media is cleaned.
In order to reduce fouling of the filter screen and downtime of the filter system, certain techniques have been established for running the filtration process. One such process utilizes the pressure differential within the hydroclone between the area inside the filter media and the area outside of the filter media. If this pressure differential is great, solids will be pushed into the Filter media and cause clogging or fouling of the filter media. A pressure differential set point may be established that is a safe pressure differential under which clogging or fouling will be minimized. A filtrate flow control valve set at a particular flow control rate is present at the exit of the filtered medium exiting the hydroclone. Once the pressure differential set point is reached, an automated valve on the effluent line is closed and a drain valve of the hydroclone is opened to cause particulates to exit the filtration system.
Although capable of removing particulates from the hydroclone before fouling of the filter media occurs, such a process must have the pressure differential set point at a level that is lower than a point at which fouling of the filter media occurs. This is because the system cannot react instantaneously to spikes in the pressure differential which would cause fouling to occur if the set point were located at or close to the pressure differential at which fouling actually occurs. The set point is thus located at a lower level to give the system time to reduce pressure through various means including closing the effluent valve once it appears the pressure differential is rising. This process sacrifices filtration capacity to achieve a reduction in filter media fouling and thus much less medium is filtered by the system per unit time. Further, although described as avoiding filter media fouling, it is to be understood that over time the filter media will in fact become fouled with particulates and will need to be serviced. The aforementioned process helps to reduce the amount of downtime in the system, but does not eliminate the occurrences of filter screen fouling. As such, there remains room for variation and improvement within the art.
Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the invention.